Ya-Sin 36:37
These four verses are a single contemplation set.
وَءَايَةٌ لَّهُمُ ٱلَّيْلُ نَسْلَخُ مِنْهُ ٱلنَّهَارَ فَإِذَا هُم مُّظْلِمُونَ
Another sign for them is the night: We strip the day out of it—and they are in darkness
Ya-Sin 36:37 · Translation: talal-itani
Image
The verb "naslakhu" means "to peel, to strip off"; day is stripped from night like a skin. Then of the Sun: "tajrī li-mustaqarrin lahā" — it runs on toward its own appointed resting-place. Of the Moon: "manāzila" — stations, that is, ordered phases. And the most striking closing: "kullun fī falakin yasbaḥūn" — each is swimming in an orbit. The verb "yasbaḥūn" describes a body swimming through a fluid.
Observation
Each image in the verse can be set alongside modern astronomy. The Sun's "mustaqarr" does not name only its daily motion: the solar system, about 28,000 light-years from the center of the Milky Way, orbits the galaxy at roughly 828,000 km/h — so the Sun moves not only by its light, but as a body in motion. The Moon's "stations" line up with the phases. That the orbits do not collide ("nor does the sun overtake the moon") can be thought together with orbital stability in celestial mechanics. The verb "yasbaḥūn" (they swim) — not motion along a line but through a medium — recalls the modern picture of spacetime as a fabric. The verse gives no theorem, only an image.
Exegesis
Ibn Kathīr gives three possible senses of the Sun's "mustaqarr": its daily point of setting, its ultimate stopping-place, and its appointed course along its orbit. The classical tradition dwells on "kullun fī falakin yasbaḥūn" — "falak" in Arabic is a "turning circle." The moon's stations are read by classical exegetes as a calendar written into the sky.
Sources
Tafsīr: Ibn Kathīr, Tafsīr al-Qur'ān al-ʿAẓīm; al-Bayḍāwī, Anwār al-Tanzīl. Science: celestial mechanics — lunar phases, Keplerian orbits, the Sun's galactic orbit.